Contemporary position displacement sensors for vehicular shock absorbers include those based on Hall-effect switches, and various forms of optical sensors. Hall-effect switches provide low accuracy, must be mounted outside of a shock absorber, and don't work in the presence of water.
The various forms of optical sensors including proximity type, and the coaxial reflective type will not reliably operate at the extreme temperatures found inside a shock absorber, which may exceed 160.degree. Celsius.
What is needed is an improved sensor for measuring a displacement of a shock absorber that is accurate and will work reliably under extreme temperature conditions.